I think this is probably one of the most viable business models for a "CubeSat" sized payload. If I had a rocket to the moon, that is the first thing I would offer: "mix your human dust with moon dust"
A million dollars split between 2500 is just $400 each.
Obviously very rough figures but it nothing screams outrageous to me. I'd be surprised if you couldn't fill 2500 of those orders.
Only problem I see is that 0.5 carat cremation diamond is $6000 US, and it would be a "waste" of the ashes since they only use a few ounces (~150g) and a human cremated is roughly 5kg.
BUT, if a person is fine with only sending a portion of their loved one to the moon for the super "low price" of $20k, it would only take 75 to break even, but there is room for a WHOLE lot more.